The present invention relates to particulates having hydrophobic and oleophobic surfaces and subterranean operations relating thereto.
After a wellbore is drilled, it may often be necessary to fracture the subterranean formation to enhance hydrocarbon production, especially in tight formations like shales and tight-gas sands. Access to the subterranean formation can be achieved by first creating an access conduit from the wellbore to the subterranean formation. Then, a fracturing fluid, often called a pre-pad, is introduced at pressures exceeding those required to maintain matrix flow in the formation permeability so as to create or enhance at least one fracture that propagates from at least one access conduit. The pre-pad fluid is followed by a pad fluid comprising proppant particles that often accumulate into proppant packs. Generally, proppant packs hold open the fracture after pressure from the fluid is reduced, thereby maintaining the ability for fluid to flow through the fracture and ultimately be produced at the surface.
In some instances, proppant particles are coated with polymers or surfactants to render the surface of the proppant particle hydrophilic. Generally, it is believed that hydrophilic surfaces may act to absorb water and allow hydrocarbons to pass, thereby minimizing the production of water at the wellbore. However, in some cases, the absorption of water to hydrophilic proppant particles can cause pressure to build up in the proppant packs and reduce the overall conductivity of any fluid through the proppant pack. In the long-term (e.g., months to years), loss of conductivity can result in reduced hydrocarbon production and, possibly, the need for remedial subterranean operation to return proppant pack conductivity. Reduced hydrocarbon production can cost time and be expensive, especially where additional remedial operations are needed.
Additionally, in the short-term (e.g., days to months), reduced conductivity through proppant packs may inhibit the flow back operations. As used herein, the term “flow back” refers to the process of allowing fluids to flow from the wellbore or near-wellbore portion of the subterranean formation to the surface following a treatment operation. Flow back processes are generally used between treatments so as to remove a previous treatment fluid or in preparation for cleanup so as to prepare the wellbore for production. Flow back processes can be particularly important when the fluids of subsequent treatment operations are incompatible, e.g., a brine treatment fluid followed by a foamed treatment fluid that is salt sensitive. Consequently, where a treatment fluid is still associated with a proppant pack, a subsequent treatment fluid may, in some instances, be ineffective in at least that portion of the subterranean formation, thereby reducing the efficacy of the subsequent treatment operation.
Therefore, the ability to efficiently and over long periods of time allow for the conductivity of water and hydrocarbons through proppant pack may be of benefit to one of ordinary skill in the art.